“The Special Envoy has estimated Iran spends $6 billion annually on supporting the Assad regime in Syria. So it’s $6 billion not $35 billion,” Jessy Chahine, the spokeswoman for de Staffan de Mistura said Monday in an email, Bloomberg reported.

Chahine’s claims come in reaction to previous reports from the Christian Science Monitor citing that de Mistura informed last month a think tank in Washington that Iran was spending three times its official military budget to back the Assad regime.

Iran’s official military budget is estimated at $35 billion annually.

Other experts, including Nadim Shehadi, the director of the Fares Center for Eastern Mediterranean Studies at Tufts University estimated that the numbers were even higher.

Shehadi said his research showed that in 2012 and 2013 the Islamic Republic spent between $14 and $15 billion in both military and economic aid to the Syrian regime.

However, Shehadi acknowledged that his figures were estimates as Iran does not reveal its budgets for its Revolutionary Guard Corps or the full subsidies it provides to allies.

Earlier in 2015, the former vice president for applied research on conflict at the U.S. Institute of Peace, Steven Heydemann, said that he estimates Iran’s support for Assad to be between $15 and $20 billion annually.

These estimates are much higher than what the Obama administration has implied Iran is spending on its policy to destabilize the Middle East.

The Obama administration, which never disclosed its own estimates on how much Iran spends to back Syria and other allies, suggested that Tehran is spending minimal amounts to destabilize the region.

“The great danger that the region has faced from Iran is not because they have so much money. Their budget — their military budget is $15 billion compared to $150 billion for the Gulf States,” Obama said in an interview with Israel’s Channel 2.

The administration also said that the amount Iran spends to disrupt security in the region is so low that any future sanctions relief – as part of the nuclear deal – will not make any difference.

“The unfortunate truth remains that the cost of this support is sufficiently small, that we will need to remain vigilant with or without a nuclear deal to use our other tools to deter the funding of terror and regional destabilization,” Treasury Secretary Jack Lew said last week.

Iran is a top ally of Syrian President Bashar al-Assad and is believed to have supplied his government with billions of dollars since the Syrian conflict began in early 2011.